1. Field of the Invention
The invention relates to the technical field of surgical instruments.
2. Description of the Prior Art
In some surgical interventions, the use of trocars is known in order to allow the insertion of various types of endoscopy instruments, in particular into cavities in the human body. This applies, for instance, to pneumoperitonium where it is necessary to inflate the abdomen in order to allow the passage of instruments. The trocar is shaped in order to permit the injection of CO.sub.2 in order to decompress the internal organs.
As is completely familiar to those skilled in the art, a trocar essentially comprises a hollow body of which the end has a tip fitted with an internal channel to allow the insertion of the instrument in question. This internal channel communicates with the hollow body. In order to ensure leaktightness when the instrument is withdrawn in order to prevent any loss of previously injected CO.sub.2, the trocar has internal features capable of fulfilling this function.
Regardless of the ways in which trocars are designed, they are generally shaped to only allow the insertion of instruments having a clearly defined diameter. If it is necessary to change instruments during an operation and if the diameter of the instrument is greater or less than that of the trocar the surgeon is often confronted with real problems.
In order to attempt to overcome these drawbacks, trocars fitted with interchangeabe tips slide valves or swiveling discs have been proposed in order to match the various diameters of surgical instruments likely to be used. One might mention, for example, the teachings of patent WO-A-92444.
However, these solutions are unsatisfactory because they require the surgeon to carry out relatively awkward manipulations involving the use of both hands. In addition, these trocars do not always meet the requirement for leaktightness and are often very bulky. Finally, they are either disposable or resterilizable and necessitate complex disassembly and cleaning procedures.